I will apologize in advance if this isn't the right place to put this.

I just downloaded and installed. Cencus+ 6.01
Ran it on Khadgar Realm.

My wife was logged in on her Druid and I on my Priest, both of us in our guild in which we are Co-GM rank. I was in Pandaria and she in the Barrens. There was also a DK on in the guild at the time.

The scan only saw me in the guild and listed 0 Druids in the realm at all.
I flew to the Barrens, joined a group with my wifes Druid and while flying over her head, re-ran a full scan. Still it saw no druids?!

I later tried to upload my data but there was no "Cencus????" file of any kind. in fact, no files beginning with "C" in the Saved variables folder for the character?!

As Padanfain said.. Almost all addon saved data is stored at the account level and not the character level. The character level area is for character specific tweaks for addon usage.

My first thought was as a Pandarian you might have been too low a level to be admitted to Horde or Alliance faction.. and if you were you wouldn't have been able to actually gather census data as you need to be a faction member. But since you were able to group you have to be a faction member.

I'm assuming you weren't play/testing on the PTR realms which are currently testing WoW v5.4... and also has changes that might impact CensusPlus.

Next time you are playing... try the following.. do a manual /who and see what you get from Blizzard as the result. Then start a census run, you should see mostly the same level/race/class counts as from the /who (with the understanding that the default who is limited to a maximum of 50 characters per selection query)

If you want to track the activity of CensusPlus without blocking game display, you can use the option button in the main Census window and enable the VERBOSE option which will dump messages in your local chat window describing what CensusPlus is doing.